Newly discovered letters written by Princess Diana to former Buckingham Palace steward Cyril Dickman reveal some very touching details about her sons Prince William and Prince Harry.

"William adores his little brother and spends the entire time swamping Harry with an endless supply of hugs and kisses"

The handwritten notes give an intimate glipse into their childhoods, including William’s joy at being an older brother.

One letter, dated September 20, 1984 (when Harry was just five days old and William was 2) reads: "Dear Cyril, it was so very kind of you to have sent us such a lovely card, on the arrival of our small son — we both were greatly touched by your thoughtfulness and enormously appreciated it. William adores his little brother and spends the entire time swamping Harry with an endless supply of hugs and kisses hardly letting the parents near!"

How adorable!

Princess Diana also wrote about the incredible impact of Prince Harry's birth, saying "The reaction to one tiny person's birth has totally overwhelmed us and I can hardly breathe for the mass of flowers that are arriving here!"

A photo posted by CheffinsFineArt (@cheffinsfineart) on Dec 16, 2016 at 2:09pm PST

But perhaps the most endearing detail of all is when eight years later, Princess Diana again penned a letter to Cyril, and hilariously told him that Harry was a bit of trouble-maker!

"The boys are both well and enjoying boarding school a lot," she wrote in a letter dated October 17, 1992. "Although Harry is constantly in trouble!"

Cyril was a palace steward for more than 50 years but sadly passed away in 2012, aged 85. His grandson, Matthew Dickman, recently found the collection of Princess Diana's letters and decided to put them up for auction. The letters are valued at £15,000 and will go on sale in Cambridge on January 5.